• 한국대기환경학회지
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• 제25권4호
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• pp.325-338
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• 2009

National parks provide recreation, health, and science to human being. The provision of beautiful landscape view of the national park improves an economic and social phase of a nation. However, visibility impairment frequently occurred in the national park area of Gyeongju. The purpose of this study is to investigate the physical and the chemical characteristics of visibility reduction observed at the national park area of Gyeongju. Optical, chemical, meteorological characteristics and scenic monitoring were performed at the visibility monitoring station of Gyeongju University located at the Seoak section of Gyeongju national park from April 28 to May 9, 2008. Light extinction, light scattering, and light absorption coefficients were continuously measured using a transmissometer, a nephelometer, and an aethalometer, respectively. In order to investigate the impact of aerosol chemistry on visibility impairment, size-resolved aerosols were collected at intervals of 2-hour (from 8 A.M. to 6 P.M.) and 14-hour (from 6 P.M. to 8 A.M.) interval each sampling day. The average light extinction coefficient and the average visual range were measured to be $270{\pm}135\;Mm^{-1}$ and $14.5{\pm}6.3\;km$ during the intensive monitoring period, respectively. It was revealed that sulfate particle was the largest contributor to the light extinction under hazy condition. Organic mass accounted for about 26% of the average light extinction. The mass extinction efficiencies for $PM_{1.0}$, $PM_{2.5}$, and $PM_{10}$ were estimated to be 9.0, 4.7, and $2.7\;m^2\;g^{-1}$ under the consideration of water growth function of hygroscopic aerosols, respectively.

• 한국토양비료학회지
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• 제45권2호
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• pp.312-316
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• 2012

1. 우리나라 북부 8개 지역을 대상으로 하여 최근 30년간의 기상자료 분석에 의한 12월~6월의 일평균 PET는 $2.31mm\;day^{-1}$ 이었다. 2. 시설재배 고추의 우리나라 북부 8개 지역별, 3개 토성 및 16개 순별, 총 384경우의 재배여건에 적합한 물 절약형 적정 관개간격 및 1회 관개량을 산정하였다.

• Ocean and Polar Research
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• 제26권2호
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• pp.367-376
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• 2004

Macrobenthos were collected at 7 stations located from $5^{\circ}N$ to $10^{\circ}N$ with 1o interval along the longitude of $131^{\circ}W$ using a box corer with sampling area of $0.25\;m^2$ in July, 1999. In order to see the vertical distribution of macrobenthos in sediments, each subcore sample was divided into 5 layers with 1 cm interval up to 6 cm depth. Each subcore sample was sieved through 0.3 mm mesh screen and fixed with 10% Rose Bengal added formalin. A total of 22 faunal groups in 11 phyla were sampled and the average density was $959\;{\pm}\;584\;ind./m^2$. Foraminiferans comprised 34.8% of total specimens were the most abundant fauna, and followed by nematodes (27.5%), polychaete worms (15.7%), and benthic harpactoid copepods (10.4%). A latitudinal trend was shown in the distribution of macrobenthos; the maximum density of $1,832\;ind./m^2$ appeared at station N06 and the most poverished community occurred at station N09 with the density of $248\;ind./m^2$. The density of typical macrofaunal taxa except foraminiferans and nematods was $116\;ind./m^2$. In the vertical distribution of macrobenthos, more than 70% of macrobenthos occurred in the upper 2 cm layer, and upper 4 cm layer contained about 90% of macrofauna. Polychaete worms consisted of 22 families, and cirratulid and paraonid worms were dominant polychaete species. The prominant feeding guilds of polychaete worms were SDT (surface, descretely motile, tenaculate feeding) and SMX (surface, motile, non-jawed); they comprised more than 50% of polychaete abundance. These feeding guilds of polychaete worms suggests that the deep sea benthos should be well adapted the newly settled deposits from water column, but this should be clarified by the further studies.

• 한국산림과학회지
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• 제99권5호
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• pp.698-705
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• 2010

The concentration of monoterpenes (12 species) was measured from spring to fall in 2008 in ambient air at six different forests located in the southern parts of Korea. Sampling - using a Solid Adsorption Tube - was conducted at 2-hour-interval a day (24 hours) of each season. The highest annual average concentration of total monoterpene was 0.715 ppbv, which occurred at Mt. Baega. ${\alpha}$-Pinene, sabinene and ${\beta}$-pinene were the most abundant compounds throughout the sampling periods and areas. The concentrations of monoterpene were higher in spring than in any other seasons. The compositions and concentrations of monoterpene displayed a distinct pattern by area. Most of monoterpenes had diurnal variations with higher concentrations during the daytime, and lower during the nighttime. This may be due to the fact that the amount of monoterpenes emitted increases at elevated ambient temperatures and increased sunlight intensity. The results of this study showed that each area had distinct monoterpene compositions, which depended on the tree species, topography and local climate at each area.

• 한국대기환경학회지
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• 제28권1호
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• pp.39-51
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• 2012

Aerosol slurry samples were collected in 60-min interval using Korean Semi-continuous Elements in Aerosol Sampler (KSEAS) between May 19 and June 6, 2010 at an urban site of Gwangju. The $PM_{2.5}$ samples were collected with a flow rate of 16.7 L/min and particles are grown by condensation of water vapor in a condenser maintained at ${\sim}5^{\circ}C$ after saturation by direct injection of steam. The resulting droplets are collected in a liquid slurry with a airdroplet separator. Concentrations of 16 elements (Al, Fe, Mn, Ca, K, Cu, Zn, Pb, Cd, Cr, Ti, V, Ni, Co, As, Se) in the collected slurry samples were determined off-line by ICP-MS. KSEAS sample analysis encompassed the sampling periods for which 24-hr average elemental species concentrations were calculated for comparison with those derived from 24-hr integrated filter samples. Relationship between elemental species measured by two methods indicated high correlation coefficients (r), mostly greater than r of 0.80. However, we note that concentrations of Al, K, Ca, Mn, and Fe, which are often associated with crustal elemental particles, in the KSEAS samples, were substantially lower (1.4~11 times) than those found in the typical filter-based samples. This discrepancy is probably due to difficulties in transferring insoluble dust particles to the collection vials in the KSEAS. Temporal profiles of elemental concentrations indicate that some transient events in their concentrations are observed over the sampling periods. For the elemental species studied, atmospheric concentrations during the transient events increased by factors of 4 in Mn~80 in Zn, compared to their background levels. Principle component analyses were applied to the hourly KSEAS data sets to identify sources affecting the concentrations of the metal constituents observed. In this study, we conclude that hourly measurements for particle-bound elemental constituents were extremely useful for revealing the short-term variability in their concentrations and developing insights into their sources.

• 한국농공학회논문집
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• 제61권6호
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• pp.73-79
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• 2019

Continuous and tremendous data (canopy temperature and meteorological variables) are necessary to determine Crop Water Stress Index (CWSI). This study investigated the optimal monitoring time and interval of canopy temperature and meteorological variables (air temperature, relative humidity, solar radiation and wind speed) to determine CWSIs. The Nash-Sutcliffe model efficiency coefficient (NSE) was used to quantitatively describe the accuracy of sampling method depending upon various time intervals (t=5, 10, 15, 20, 30 and 60 minutes) and CWSIs per every minute were used as a reference. The NSE coefficient of wind speed was 0.516 at the sampling time of 60 minutes, while the ones of other meteorological variables and canopy temperature were greater than 0.8. The pattern of daily CWSIs increased from 8:00 am, reached the maximum value at 12:00 pm, then decreased after 2:00 pm. The statistical analysis showed that the data collection at 11:40 am produced the closest CWSI value to the daily average of CWSI, which indicates that just one time of measurement could be representative throughout the day. Overall, the findings of this study contributes to the economical and convenient method of quantifying CWSIs and irrigation management.

• Asian-Australasian Journal of Animal Sciences
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• 제13권6호
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• pp.811-816
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• 2000

Five experiments were conducted to evaluate blood urea nitrogen (BUN) as a potential index of feed efficiency (G/F) and lean growth in growing-finishing pigs. Exp. 1 was conducted to examine the relationship between feeding protocol and BUN values. Fasted-refed pigs exhibited BUN peaks 3 h post-prandially while those given ad libitum access to diet had inconsistent BUN patterns in 10 h blood sampling with an 1 h interval. In Exp. 2 and 3, it was revealed that the peak BUN values were negatively correlated (p<0.01) with G/F in both barrows and gilts at 20 kg body weight (BW) and 50 kg to 90 kg BW. In Exp. 4, it was found that BUN values between 55 kg and 70 kg BW, when lean gain is maximized, were best correlated with average daily lean gain (ADLG). In Exp. 5, 18 barrows and 21 gilts were used to examine the relationship between BUN values at 65 kg BW and ADLG from birth to market weight. The BUN values at 65 kg BW and ADLG were negatively correlated (p<0.01) in both genders. These experiments demonstrated that there was a correlation between peak BUN values, and G/F and ADLG under specific circumstances.

• 한국토양비료학회지
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• 제46권5호
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• pp.313-321
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• 2013

The Average daily PET (Potential evapotranspiration), evaluated based on the last 30 years meteorological data and the lysimeter experiment carried out by RDA during 11 years, of 9 regions in Korea for the tomato cultivated in greenhouse, was $3.41mm\;day^{-1}$. Two kinds of water saving irrigation standard (WSIS), deficit irrigation standard (DIS) and partial root-zone drying irrigation standard (PRDIS) that include the irrigation interval and the amount of irrigation water according to the region, soil texture and growing stage, were established. According to the DIS and PRDIS, the cultivator can save water up to 29.2% and 53.7%, respectively, for tomato cultivation in greenhouse compared to the full irrigation standard (FIS) which established in 1999. WSIS can be used easily by the cultivator without complicate procedures such as soil sampling and measurement of soil water status by expensive sensors. But the cultivator should care about irrigation method such as PRDI (partial root-zone drying irrigation) without yield decrease.

• 대한전기학회논문지:전력기술부문A
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• 제48권12호
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• pp.1479-1485
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• 1999

This paper proposes a fuzzy decision making method for power transformer protection to identify an internal fault from other transient states such as inrush, over-excitation and an external fault with current transformer (CT) saturation. In this paper, analyzing over 300 EMTP simulations of disturbances, four input variables are selected and fuzzified. At every sampling interval from half to one cycle after a disturbance, from the EMPT simulations, different fuzzy rule base is composed of twelve if-then fuzzy rules associated with their basic probability assignments for singleton- or compound-support hypotheses. Dempster's rule of combination is used to process the fuzzy rules and get the final decision. A series of test results clearly indicate that the method can identify not only an internal fault but also the other transients. The average of relay operation times is about 12(ms). The proposed method is implemented into a Digital Signal Processor (TMS320C31) and tested.

• ALGAE
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• 제20권4호
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• pp.345-352
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• 2005

In order to investigate the distribution of phytoplankton community in the coastal waters of the Chuksan Harbor, East Sea, the abundance and biomass of phytoplankton have been evaluated through seasonal interval sampling from April 2000 to October 2002. A total of 363 different phytoplankton species was observed and most of them were composed of diatoms. The mean abundance and chlorophyll-a concentration of phytoplankton during the study period ranged from 56 ${\times}$ $10^3$ to 720 ${\times}$ $10^3$ cells $L^{-1}$ and from 0.78 to 3.29 μg chl-a $L^{-1}$, respectively. The relative contribution of the size-fractionated phytoplankton to phytoplankton community showed difference according to seasons. The average contribution of nano-phytoplankton(<20 $\mu$m) was over 50% in the total abundance and biomass of the phytoplankton. Our results show that nano-phytoplankton play an important role in the southern coastal waters of the East Sea. And the environmental factors such as suspended substances, phosphates and silicates were positively correlated with the abundances and biomass of phytoplankton.